One-way clutch mechanisms employ as their primary components a driving ring, a driven ring, and a plurality of identical connectors. The driving ring and the driven ring are coaxial, are rotationally detached, and are configured in such a way as to house the connectors between them. The connectors act as one-way links between the driving ring and the driven ring. In one rotational direction, the connectors jam the driving ring and the driven ring, causing all components to rotate in unison and hence transmit torque from the driving ring to the driven ring. In the opposite rotational direction, the connectors are detached such that the driving ring cannot impart torque or rotation to the driven ring. When the connectors jam the driving ring and the driven ring, the clutch is said to be engaged. When the connectors are detached, the clutch is said to be disengaged or to freewheel. One-way clutch systems function in the two distinct modes of engagement and freewheeling.
In existing one-way clutch systems, the change from the freewheeling mode to the engaged mode is aided by means that bias the connectors toward engagement. The bias is necessary for the inception of clutch engagement, but in the freewheeling mode it introduces undesirable noise, wear, heat, and the need for special lubrication and heat removal.
The connector in existing one-way clutches is typically a roller, a sprag, or a pawl. Rollers and sprags are similar in the way they transmit torque. In the engaged mode, the rollers or sprags are wedged between corresponding converging surfaces on the driving ring and the driven ring, thereby transmitting torque by the nearly radial thrust in rollers or sprags. Consequently, large stresses and deformations develop in the mechanism, necessitating use of a large number of rollers or sprags, and requiring massive components with high material strength and hardness.
In contrast to rollers or sprags, pawls transmit torque more efficiently. In the engaged mode, the pawls are disposed between corresponding notches in the driving ring and the driven ring, thereby transferring torque by the nearly tangential thrust in the pawls. The resulting stresses and deformations are relatively low, accommodating use of fewer pawls and lighter components with low material strength and hardness.
Given the undesirable characteristics of roller or sprag clutches in terms of their torque transfer efficiency, they, however, have the desirable attribute of undergoing only negligible degree of backlash during engagement. In contrast, existing pawl clutches with their desirable torque transfer efficiency undergo a considerable degree of backlash during engagement. An additional undesirable characteristic of all existing one-way clutches is the biasing of the connectors toward engagement when the system is in freewheeling mode.
The one-way clutch mechanism that is the subject of this invention falls within the pawl-type category of one way clutch systems with the added novelties that it does not require a biasing mechanism toward engagement, and its backlash can be reduced to any desirable degree. Consequently, in addition to its torque transmission efficiency in the engaged mode, it undergoes negligible backlash in the engaging process and thus prohibits excessive noise, wear, and heat in the freewheeling mode of its operation.